1. Field of the Invention
The present invention relates to a wide area network (WAN) access system capable of performing a line switching and a packet switching, and more particularly to a WAN access system, in which a physical layer has a connection speed of the T1/E1 level, and a data layer above a physical layer can back up both the line switching and the packet switching.
2. Description of the Related Art
A WAN access system generally has a hardware, in which a specific physical layer backs up a service of a specific data layer. In this case, the physical layer has to realize different access systems according to whether the data exchanging method backed up by the data layer on a WAN protocol is a line switching method or a packet switching method, in a WAN access system having a corresponding physical layer of T1/E1 level, even though the physical layer is not changed, but is the same.
Especially, it is a noticeable tendency in recent times that, in the case of the same physical layer, the hardware of the system is not changed, but only the software in the system is changed, according to the data exchanging method in the data layer placed above the physical layer.
Meanwhile, in the case where the data layer backs up the line switching method, from the viewpoint of the hardware, the conventional WAN access system includes a user connection process module section 10 for processing requests of corresponding users, a central control process module section 20 for performing a general control process, and a WAN connection process module section 30 for performing a transfer, an extraction, and a conversion of data, as shown in FIG. 1.
The user connection process module section 10 includes an analog/digital connection section 11, a serial connection section 12, and a local area network (LAN) connection section 13. The analog/digital connection section 11 performs an analog connection with a telephone or a facsimile telegraph and a digital connection with a private switching system, that is, a private branch exchange (PBX). The serial connection section 12 processes a V.35 or recommended standard (RS)-449 interface, and the LAN connection section 13 performs a LAN connection.
The central control process module section 20 includes a time division multiplexing (TDM) switching section 21, a voice processing section 22, and a processor module section 23. The TDM switching section 21 performs a switching between TDM buses, and the voice processing section 22 performs compression/restoration of voice data transmitted/received through the analog/digital connection section 11. The processor module section 23 backs up a part of an asynchronous transfer mode (ATM) layer and controls all sections in respective module sections. In this case, the TDM bus means signals including a frame synchronous signal, a data clock signal, a transmission data signal, and a reception data signal.
The WAN connection process module section 30 includes a physical medium connection section 31 and a frame conversion section 32. The physical medium connection section 31 performs a physical medium connection with WAN, and the frame conversion section 32 converts a frame available in the physical layer into an electric signal or converts an electric signal received through the physical medium connection section 31 into frame data.
Hereinafter, described will be an operation of the conventional WAN access system having the construction as described above, in which the physical layer has a connection speed of T1/E1 level, and the line switching method used in, e.g., a public telephone network is utilized.
First, information or data processed by the analog/digital connection section 11 of the user connection process module section 10 are transferred through a first TDM bus, the TDM switching section 21 of the central control process module section 20, and a fourth TDM bus, to the frame conversion section 32 of the WAN connection process module section 30. Otherwise, the data are transferred to the voice processing section 22 through a third TDM bus by the TDM switching section 21 and then is voice-compressed, and thereafter are transferred through the fourth TDM bus to the frame conversion section 32 of the WAN connection process module section 30 and then are transmitted to the WAN through the physical medium connection section 31.
Data received through the serial connection section 12 and the LAN connection section 13 of the user connection process module section 10 are transferred respectively through a serial bus and a LAN interface to the processor module section 23 of the central control process module section 20. Then, data to be transmitted to the WAN are transferred through a second TDM bus, the TDM switching section 21, and the fourth TDM bus to the frame conversion section 32 of the WAN connection process module section 30, and then transmitted through the physical medium connection section 31 to the WAN.
On the contrary, data received through the frame conversion section 32 of the WAN connection process module section 30 are transferred to a corresponding user through a reverse process to the above process, in the WAN access system.
Meanwhile, in the case where the data layer uses a packet switching method, the hardware of the conventional WAN access system includes the processor module section 23 and a physical layer convergence protocol (PLCP) processing section 33, further to the hardware shown in FIG. 1, as shown in FIG. 2. In the following description, the same construction as in the hardware of FIG. 1 will be numbered the same and a description about the same construction will be omitted.
A segmentation and reassembly (SAR) processing section 24 is contained in the central control process module section 20 and performs a cell disassembling/assembling function of an ATM adaptation layer 1 (AAL1) and an AAL5. The PLCP processing section 33 is contained in the WAN connection process module section 30. The PLCP processing section 33 transforms data received through a universal-test-and-operation-physical-interface-for-ATM (UTOPIA) bus into a frame available in the physical layer and transfers it to the frame conversion section 32. Further, the PLCP processing section 33 extracts data to be transferred through the UTOPIA bus to the SAR processing section 24 of the central control process module section 20 from the frame in the physical layer received through the frame conversion section 32. In this case, the UTOPIA bus means signals including transmission/reception signals set as criteria for exchanging transmission/reception data between the physical layer and the data layer.
Hereinafter, described will be an operation of the conventional WAN access system having the construction as described above, in which the physical layer has a connection speed of T1/E1 level, and the packet switching method such as the ATM is utilized.
Data processed by the analog/digital connection section 11 of the user connection process module section 10 are transferred through the first TDM bus, the TDM switching section 21 of the central control process module section 20, and the second TDM bus, to the processor module section 23. Thereafter, the data are transformed into the mode of the AAL1 by the SAR processing section 24 and then transferred to the PLCP processing section 33 of the WAN connection process module section 30 by the UTOPIA bus, or the data are transferred through the third TDM to the voice processing section 22 by the TDM switching section 21 and voice-compressed, and then transferred through a host processor (HP) interface to the SAR processing section 24 and transformed into the mode of AAL5. Thereafter, the data are transferred through the UTOPIA bus to the PLCP processing section 33 of the WAN connection process module section 30. In this case, the HP interface means signals including the address/data bus for the data exchange between a processor of the processor module section 23 and an auxiliary processor of the voice processing section 22, and related control signals.
In the meantime, data received through the serial connection section 12 and the LAN connection section 13 of the user connection process module section 10 are transferred respectively through the serial bus and the LAN interface to the processor module section 23 of the central control process module section 20. Thereafter, data to be transmitted to the WAN are transformed into the mode of AAL5 by the SAR processing section 24 and then transferred through the UTOPIA bus to the PLCP processing section 33 of the WAN connection process module section 30. Then, the PLCP processing section 33 transforms the data received through the UTOPIA bus into a T1/E1 frame of the physical layer, and then transfers the data to the frame conversion section 32 through the fourth TDM bus, which is a local TDM bus, so that the data are transmitted through the physical medium connection section 31 to the WAN.
In the conventional WAN access system as described above, since a specific physical layer backs up a specific data layer, the conventional WAN access system has a deteriorated hardware flexibility. Further, there is a disadvantage in that the conventional WAN access system has to simultaneously change the hardware construction and the software or employ a new access system, according to a change of the WAN protocol used in the data layer.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and it is an object of the present invention to provide a WAN access system capable of performing a line switching and a packet switching, in which data can be processed by modifying only the software without modifying the hardware construction, even when a data exchanging method, which is a WAN protocol used in a data layer above a physical layer, is changed, in the case where the connection speed of the physical layer is the T1/E1 level.
It is another object of the present invention to provide a WAN access system capable of performing a line switching and a packet switching, in which TDM buses, UTOPIA buses, and a processor bus capable of interfacing with the processor module section, are defined as internal interfaces of a WAN connection process module section, so that, even when the connection speed of a physical layer exceeds the T1/E1 level and a data layer is changed into a packet switching mode such as an ATM, the change can be easily coped with by modifying the WAN connection process module section.
In accordance with one aspect of the present invention, there is provided a WAN access system capable of performing a line switching and a packet switching, the WAN access system comprising: a user connection process module section for processing a corresponding request of users; a WAN connection process module section for performing transfer, extraction, and transformation of data; and a central control process module section for controlling the WAN access system, wherein the central control process module section comprises: a TDM switching section for performing switching between the TDM buses so as to enable the line switching and the packet switching; a voice processing section for performing compression/restoration for voice data transmitted/received; a processor module section for performing an AAL5 SAR processing and an SAAL processing and controlling a switching path for the TDM switching section; and an AAL1-processing/UTOPIA-multiplexing section for performing an AAL1 SAR processing and a UTOPIA bus multiplexing processing, and the WAN connection process module section comprises: a physical medium connection section for performing a physical medium connection; a frame conversion section for converting a frame available in a physical layer into an electric signal and converting an electric signal received through the physical medium connection section into frame data; a TDM selection section for selecting and processing a predetermined TDM bus according to a control of the processor module section; and a PLCP processing section for transforming data received through a second UTOPIA bus into a frame available in the physical layer and transferring the frame to the frame conversion section through the TDM selection section, the PLCP processing section extracting data to be transferred through the second UTOPIA bus to the AAL1-processing/UTOPIA-multiplexing section from the frame in the physical layer received through the frame conversion section.
In this case, a line switching TDM bus for transmission/reception of data is connected between the TDM switching section and the TDM selection section.
Further, when the data layer employs the packet switching method, the processor module section transforms data, which have been transferred to the voice processing section by the TDM switching section and voice-compressed, into AAL5 cells, and transforms data to be transmitted to a WAN, from among data transferred through a serial bus and a LAN interface from the user connection process module section, into AAL5 cells, and then transfers the AAL5 cells through a first UTOPIA bus to the AAL1-processing/UTOPIA-multiplexing section.
In addition, the AAL1-processing/UTOPIA-multiplexing section multiplexes the AAL5 cells, which have been received through the first UTOPIA bus, and the AAL1 cells, which have been transformed from the data transferred from the TDM switching section, and transfers the multiplexed cells through the second UTOPIA bus to the WAN connection process module section. The AAL1-processing/UTOPIA-multiplexing section performs a recombination of AAL1 cells, which have been extracted from the data transferred through the second UTOPIA bus from the WAN connection process module section, and then transfers the recombined cells through a TDM bus to the TDM switching section, and the AAL1-processing/UTOPIA-multiplexing section transfers the AAL5 cells through the first UTOPIA bus to the processor module section.
In accordance with another aspect of the present invention, there is provided a WAN access system capable of performing a line switching and a packet switching, the WAN access system comprising: a user connection process module section for processing a corresponding request of users; a WAN connection process module section for performing transfer, extraction, and transformation of data; and a central control process module section for controlling the WAN access system, wherein the central control process module section comprises: a TDM switching section for performing switching between the TDM buses so as to enable the line switching and the packet switching; a voice processing section for performing compression/restoration for voice data transmitted/received; and a processor module section for performing an AAL5 SAR processing and an SAAL processing and controlling a switching path for the TDM switching section, and the WAN connection process module section comprises: a physical medium connection section for performing a physical medium connection; a frame conversion section for converting a frame available in a physical layer into an electric signal and converting an electric signal received through the physical medium connection section into frame data; a TDM selection section for selecting and processing a predetermined TDM bus according to a control of the processor module section; an AAL1-processing/UTOPIA-multiplexing section for performing an AAL1 SAR processing and a UTOPIA bus multiplexing processing; and a PLCP processing section for transforming data received through a second UTOPIA bus into a frame available in the physical layer and transferring the frame to the frame conversion section through the TDM selection section, the PLCP processing section extracting data to be transferred through the second UTOPIA bus to the AAL1-processing/UTOPIA-multiplexing section from the frame in the physical layer received through the frame conversion section.